Betaxolol

Ophthalmic
Ocular hypertension, Open-angle glaucoma

Oral
Hypertension

Oral:
Severe or on dialysis: Initially, 5 mg/day, may increase by increments of 5 mg every 2 wk. Max: 20 mg/day.

May be taken with or without food.

Sick sinus syndrome, severe bradycardia, cardiogenic shock, uncontrolled cardiac failure, 2nd or 3rd degree AV block, severe bronchial asthma, severe COPD, metabolic acidosis, untreated phaeochromocytoma, severe peripheral arterial disease.

Patients w/ bronchospastic disease, DM, corneal disease. May mask signs of hyperthyroidism and acute hypoglycaemia. Avoid abrupt withdrawal as it may exacerbate angina, MI, ventricular arrhythmias and precipitate thyroid storm. Patients undergoing surgery involving general anaesth. Renal and hepatic impairment. Pregnancy and lactation.

Eye discomfort (stinging and burning), bradycardia, palpitation, chest pain, oedema, insomnia, fatigue, lethargy, nausea, dyspepsia, diarrhoea, arthralgia, paraesthesia, dyspnoea, pharyngitis, antinuclear antibody positive, cold extremities.

Ophth/PO: C

Monitor BP, pulse and baseline renal function.

Symptoms: Symptomatic bradycardia, bronchospasm, hypotension and acute cardiac failure. Management: Perform gastric lavage. Administer IV atropine sulfate to induce vagal blockade; dopamine, dobutamine or norepinephrine for hypotension and glucagon for refractory cases; isoprenaline HCl and aminophylline for bronchospasm; conventional therapy w/ digitalis, diuretics and oxygen for acute cardiac failure.

Increased risk of bradycardia w/ digitalis glycosides. May cause mydriasis w/ epinephrine. Potential additive effect w/ oral Ca channel blockers, β-adrenergic blockers, antiarrhythmics (including amiodarone), parasympathomimetics, guanethidine. Increased risk of myocardial depression and hypotension w/ peripheral muscle relaxants (e.g. tubocurarine).

May increase plasma levels w/ alcohol.

May interfere result w/ glaucoma screening test (oral).

Description:
Mechanism of Action: Betaxolol is a cardioselective β-blocker which has greater affinity for β₁-receptors and has little or no effect on β₂-receptors. It lacks intrinsic sympathomimetic but has little membrane-stabilising activity. It also causes the reduction of intraocular pressure by decreasing the production of aqueous humour.
Onset: 1-1.5 hr (oral).
Pharmacokinetics:
Absorption: Completely absorbed from the GI tract. Oral bioavailability: Approx 90%.
Distribution: Crosses the placenta and is distributed into the breast milk. Plasma protein binding: Approx 50%.  
Metabolism: Undergoes minimal first-pass metabolism.
Excretion: Via urine (approx 15% as unchanged drug). Elimination half-life: 14-22 hr.

Store between 15-25°C.

Antiglaucoma Preparations / Beta-Blockers

Anon. Betaxolol. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 04/12/2013.

Batxolol tablet (Epic Pharma). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 04/12/2013.

Buckingham R (ed). Betaxolol hydrochloride. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 04/12/2013.

Kerlone Tablet. U.S. FDA. https://www.fda.gov/. Accessed 04/12/2013.

McEvoy GK, Snow EK, Miller J et al (eds). Betaxolol hydrochloride (EENT). AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com. Accessed 04/12/2013.